X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fevaluate.cpp;h=51d9b4290e6d48b3b324de5e6c459d5fd9d824a2;hp=a9c4c4e787fc69f0d1530f5a1a8b3cca15dd8e42;hb=c9dcda6ac488c0058ebd567e1f52e30b8cd0db20;hpb=f99cb3dc27719021e126690b7fd5aa5f43663ed8 diff --git a/src/evaluate.cpp b/src/evaluate.cpp index a9c4c4e7..51d9b429 100644 --- a/src/evaluate.cpp +++ b/src/evaluate.cpp @@ -1,7 +1,7 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -127,8 +127,8 @@ namespace { S( 25, 41), S( 25, 41), S(25, 41), S(25, 41) } }; - // Outpost[PieceType][Square] contains bonuses of knights and bishops, indexed - // by piece type and square (from white's point of view). + // Outpost[PieceType][Square] contains bonuses for knights and bishops outposts, + // indexed by piece type and square (from white's point of view). const Value Outpost[][SQUARE_NB] = { { // A B C D E F G H @@ -150,11 +150,8 @@ namespace { // Threat[attacking][attacked] contains bonuses according to which piece // type attacks which one. const Score Threat[][PIECE_TYPE_NB] = { - {}, {}, - { S(0, 0), S( 7, 39), S( 0, 0), S(24, 49), S(41,100), S(41,100) }, // KNIGHT - { S(0, 0), S( 7, 39), S(24, 49), S( 0, 0), S(41,100), S(41,100) }, // BISHOP - { S(0, 0), S( 0, 22), S(15, 49), S(15, 49), S( 0, 0), S(24, 49) }, // ROOK - { S(0, 0), S(15, 39), S(15, 39), S(15, 39), S(15, 39), S( 0, 0) } // QUEEN + { S(0, 0), S( 7, 39), S(24, 49), S(24, 49), S(41,100), S(41,100) }, // Minor + { S(0, 0), S(15, 39), S(15, 45), S(15, 45), S(15, 45), S(24, 49) }, // Major }; // ThreatenedByPawn[PieceType] contains a penalty according to which piece @@ -166,7 +163,6 @@ namespace { #undef S const Score Tempo = make_score(24, 11); - const Score BishopPin = make_score(66, 11); const Score RookOn7th = make_score(11, 20); const Score QueenOn7th = make_score( 3, 8); const Score RookOnPawn = make_score(10, 28); @@ -185,8 +181,8 @@ namespace { // happen in Chess960 games. const Score TrappedBishopA1H1 = make_score(50, 50); - // The SpaceMask[Color] contains the area of the board which is considered - // by the space evaluation. In the middle game, each side is given a bonus + // SpaceMask[Color] contains the area of the board which is considered + // by the space evaluation. In the middlegame, each side is given a bonus // based on how many squares inside this area are safe and available for // friendly minor pieces. const Bitboard SpaceMask[] = { @@ -195,9 +191,9 @@ namespace { }; // King danger constants and variables. The king danger scores are taken - // from the KingDanger[]. Various little "meta-bonuses" measuring - // the strength of the enemy attack are added up into an integer, which - // is used as an index to KingDanger[]. + // from KingDanger[]. Various little "meta-bonuses" measuring the strength + // of the enemy attack are added up into an integer, which is used as an + // index to KingDanger[]. // // KingAttackWeights[PieceType] contains king attack weights by piece type const int KingAttackWeights[] = { 0, 0, 2, 2, 3, 5 }; @@ -210,19 +206,6 @@ namespace { const int BishopCheck = 2; const int KnightCheck = 3; - // KingExposed[Square] contains penalties based on the position of the - // defending king, indexed by king's square (from white's point of view). - const int KingExposed[] = { - 2, 0, 2, 5, 5, 2, 0, 2, - 2, 2, 4, 8, 8, 4, 2, 2, - 7, 10, 12, 12, 12, 12, 10, 7, - 15, 15, 15, 15, 15, 15, 15, 15, - 15, 15, 15, 15, 15, 15, 15, 15, - 15, 15, 15, 15, 15, 15, 15, 15, - 15, 15, 15, 15, 15, 15, 15, 15, - 15, 15, 15, 15, 15, 15, 15, 15 - }; - // KingDanger[Color][attackUnits] contains the actual king danger weighted // scores, indexed by color and by a calculated integer number. Score KingDanger[COLOR_NB][128]; @@ -261,7 +244,7 @@ namespace { namespace Eval { /// evaluate() is the main evaluation function. It always computes two - /// values, an endgame score and a middle game score, and interpolates + /// values, an endgame score and a middlegame score, and interpolates /// between them based on the remaining material. Value evaluate(const Position& pos) { @@ -269,9 +252,10 @@ namespace Eval { } - /// trace() is like evaluate() but instead of a value returns a string suitable - /// to be print on stdout with the detailed descriptions and values of each - /// evaluation term. Used mainly for debugging. + /// trace() is like evaluate(), but instead of returning a value, it returns + /// a string (suitable for outputting to stdout) that contains the detailed + /// descriptions and values of each evaluation term. It's mainly used for + /// debugging. std::string trace(const Position& pos) { return Tracing::do_trace(pos); } @@ -316,7 +300,7 @@ Value do_evaluate(const Position& pos) { Thread* th = pos.this_thread(); // Initialize score by reading the incrementally updated scores included - // in the position object (material + piece square tables) and adding + // in the position object (material + piece square tables) and adding a // Tempo bonus. Score is computed from the point of view of white. score = pos.psq_score() + (pos.side_to_move() == WHITE ? Tempo : -Tempo); @@ -361,14 +345,14 @@ Value do_evaluate(const Position& pos) { score += evaluate_unstoppable_pawns(pos, WHITE, ei) - evaluate_unstoppable_pawns(pos, BLACK, ei); - // Evaluate space for both sides, only in middle-game. + // Evaluate space for both sides, only in middlegame if (ei.mi->space_weight()) { int s = evaluate_space(pos, ei) - evaluate_space(pos, ei); score += apply_weight(s * ei.mi->space_weight(), Weights[Space]); } - // Scale winning side if position is more drawish that what it appears + // Scale winning side if position is more drawish than it appears ScaleFactor sf = eg_value(score) > VALUE_DRAW ? ei.mi->scale_factor(pos, WHITE) : ei.mi->scale_factor(pos, BLACK); @@ -378,7 +362,8 @@ Value do_evaluate(const Position& pos) { && pos.opposite_bishops() && sf == SCALE_FACTOR_NORMAL) { - // Only the two bishops ? + // Ignoring any pawns, do both sides only have a single bishop and no + // other pieces? if ( pos.non_pawn_material(WHITE) == BishopValueMg && pos.non_pawn_material(BLACK) == BishopValueMg) { @@ -435,7 +420,7 @@ Value do_evaluate(const Position& pos) { { ei.kingRing[Them] = b | shift_bb(b); b &= ei.attackedBy[Us][PAWN]; - ei.kingAttackersCount[Us] = b ? popcount(b) / 2 : 0; + ei.kingAttackersCount[Us] = b ? popcount(b) : 0; ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0; } else @@ -443,7 +428,7 @@ Value do_evaluate(const Position& pos) { } - // evaluate_outposts() evaluates bishop and knight outposts squares + // evaluate_outposts() evaluates bishop and knight outpost squares template Score evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) { @@ -456,7 +441,7 @@ Value do_evaluate(const Position& pos) { Value bonus = Outpost[Piece == BISHOP][relative_square(Us, s)]; // Increase bonus if supported by pawn, especially if the opponent has - // no minor piece which can exchange the outpost piece. + // no minor piece which can trade with the outpost piece. if (bonus && (ei.attackedBy[Us][PAWN] & s)) { if ( !pos.pieces(Them, KNIGHT) @@ -510,18 +495,11 @@ Value do_evaluate(const Position& pos) { mobility[Us] += MobilityBonus[Piece][mob]; - // Decrease score if we are attacked by an enemy pawn. Remaining part + // Decrease score if we are attacked by an enemy pawn. The remaining part // of threat evaluation must be done later when we have full attack info. if (ei.attackedBy[Them][PAWN] & s) score -= ThreatenedByPawn[Piece]; - // Otherwise give a bonus if we are a bishop and can pin a piece or can - // give a discovered check through an x-ray attack. - else if ( Piece == BISHOP - && (PseudoAttacks[Piece][pos.king_square(Them)] & s) - && !more_than_one(BetweenBB[s][pos.king_square(Them)] & pos.pieces())) - score += BishopPin; - // Penalty for bishop with same coloured pawns if (Piece == BISHOP) score -= BishopPawns * ei.pi->pawns_on_same_color_squares(Us, s); @@ -568,8 +546,8 @@ Value do_evaluate(const Position& pos) { Square ksq = pos.king_square(Us); - // Penalize rooks which are trapped inside a king. Penalize more if - // king has lost castling availability. + // Penalize rooks which are trapped by a king. Penalize more if the + // king has lost its castling capability. if ( ((file_of(ksq) < FILE_E) == (file_of(s) < file_of(ksq))) && (rank_of(ksq) == rank_of(s) || relative_rank(Us, ksq) == RANK_1) && !ei.pi->semiopen_on_side(Us, file_of(ksq), file_of(ksq) < FILE_E)) @@ -641,10 +619,9 @@ Value do_evaluate(const Position& pos) { Score score = ei.pi->king_safety(pos, ksq); // Main king safety evaluation - if ( ei.kingAttackersCount[Them] >= 2 - && ei.kingAdjacentZoneAttacksCount[Them]) + if (ei.kingAttackersCount[Them]) { - // Find the attacked squares around the king which has no defenders + // Find the attacked squares around the king which have no defenders // apart from the king itself undefended = ei.attackedBy[Them][ALL_PIECES] & ei.attackedBy[Us][KING] @@ -655,19 +632,19 @@ Value do_evaluate(const Position& pos) { // Initialize the 'attackUnits' variable, which is used later on as an // index to the KingDanger[] array. The initial value is based on the // number and types of the enemy's attacking pieces, the number of - // attacked and undefended squares around our king, the square of the - // king, and the quality of the pawn shelter. + // attacked and undefended squares around our king and the quality of + // the pawn shelter (current 'score' value). attackUnits = std::min(20, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2) + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + popcount(undefended)) - + KingExposed[relative_square(Us, ksq)] - mg_value(score) / 32; - // Analyse enemy's safe queen contact checks. First find undefended - // squares around the king attacked by enemy queen... + // Analyse the enemy's safe queen contact checks. Firstly, find the + // undefended squares around the king that are attacked by the enemy's + // queen... b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces(Them); if (b) { - // ...then remove squares not supported by another enemy piece + // ...and then remove squares not supported by another enemy piece b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT] | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]); if (b) @@ -676,16 +653,17 @@ Value do_evaluate(const Position& pos) { * (Them == pos.side_to_move() ? 2 : 1); } - // Analyse enemy's safe rook contact checks. First find undefended - // squares around the king attacked by enemy rooks... + // Analyse the enemy's safe rook contact checks. Firstly, find the + // undefended squares around the king that are attacked by the enemy's + // rooks... b = undefended & ei.attackedBy[Them][ROOK] & ~pos.pieces(Them); - // Consider only squares where the enemy rook gives check + // Consider only squares where the enemy's rook gives check b &= PseudoAttacks[ROOK][ksq]; if (b) { - // ...then remove squares not supported by another enemy piece + // ...and then remove squares not supported by another enemy piece b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT] | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][QUEEN]); if (b) @@ -694,7 +672,7 @@ Value do_evaluate(const Position& pos) { * (Them == pos.side_to_move() ? 2 : 1); } - // Analyse enemy's safe distance checks for sliders and knights + // Analyse the enemy's safe distance checks for sliders and knights safe = ~(pos.pieces(Them) | ei.attackedBy[Us][ALL_PIECES]); b1 = pos.attacks_from(ksq) & safe; @@ -746,7 +724,7 @@ Value do_evaluate(const Position& pos) { Bitboard b, undefendedMinors, weakEnemies; Score score = SCORE_ZERO; - // Undefended minors get penalized even if not under attack + // Undefended minors get penalized even if they are not under attack undefendedMinors = pos.pieces(Them, BISHOP, KNIGHT) & ~ei.attackedBy[Them][ALL_PIECES]; @@ -758,18 +736,17 @@ Value do_evaluate(const Position& pos) { & ~ei.attackedBy[Them][PAWN] & ei.attackedBy[Us][ALL_PIECES]; - // Add bonus according to type of attacked enemy piece and to the - // type of attacking piece, from knights to queens. Kings are not - // considered because are already handled in king evaluation. + // Add a bonus according if the attacking pieces are minor or major if (weakEnemies) - for (PieceType pt1 = KNIGHT; pt1 < KING; ++pt1) - { - b = ei.attackedBy[Us][pt1] & weakEnemies; - if (b) - for (PieceType pt2 = PAWN; pt2 < KING; ++pt2) - if (b & pos.pieces(pt2)) - score += Threat[pt1][pt2]; - } + { + b = weakEnemies & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]); + if (b) + score += Threat[0][type_of(pos.piece_on(lsb(b)))]; + + b = weakEnemies & (ei.attackedBy[Us][ROOK] | ei.attackedBy[Us][QUEEN]); + if (b) + score += Threat[1][type_of(pos.piece_on(lsb(b)))]; + } if (Trace) Tracing::scores[Us][THREAT] = score; @@ -807,7 +784,7 @@ Value do_evaluate(const Position& pos) { { Square blockSq = s + pawn_push(Us); - // Adjust bonus based on kings proximity + // Adjust bonus based on the king's proximity ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 5 * rr) - Value(square_distance(pos.king_square(Us ), blockSq) * 2 * rr); @@ -815,7 +792,7 @@ Value do_evaluate(const Position& pos) { if (relative_rank(Us, blockSq) != RANK_8) ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * rr); - // If the pawn is free to advance, increase bonus + // If the pawn is free to advance, then increase the bonus if (pos.empty(blockSq)) { squaresToQueen = forward_bb(Us, s); @@ -835,12 +812,14 @@ Value do_evaluate(const Position& pos) { else defendedSquares = squaresToQueen & ei.attackedBy[Us][ALL_PIECES]; - // If there aren't enemy attacks huge bonus, a bit smaller if at - // least block square is not attacked, otherwise smallest bonus. + // If there aren't any enemy attacks, then assign a huge bonus. + // The bonus will be a bit smaller if at least the block square + // isn't attacked, otherwise assign the smallest possible bonus. int k = !unsafeSquares ? 15 : !(unsafeSquares & blockSq) ? 9 : 3; - // Big bonus if the path to queen is fully defended, a bit less - // if at least block square is defended. + // Assign a big bonus if the path to the queen is fully defended, + // otherwise assign a bit less of a bonus if at least the block + // square is defended. if (defendedSquares == squaresToQueen) k += 6; @@ -885,14 +864,14 @@ Value do_evaluate(const Position& pos) { if (Trace) Tracing::scores[Us][PASSED] = apply_weight(score, Weights[PassedPawns]); - // Add the scores to the middle game and endgame eval + // Add the scores to the middlegame and endgame eval return apply_weight(score, Weights[PassedPawns]); } // evaluate_unstoppable_pawns() scores the most advanced among the passed and // candidate pawns. In case opponent has no pieces but pawns, this is somewhat - // related to the possibility pawns are unstoppable. + // related to the possibility that pawns are unstoppable. Score evaluate_unstoppable_pawns(const Position& pos, Color us, const EvalInfo& ei) { @@ -937,7 +916,7 @@ Value do_evaluate(const Position& pos) { } - // interpolate() interpolates between a middle game and an endgame score, + // interpolate() interpolates between a middlegame and an endgame score, // based on game phase. It also scales the return value by a ScaleFactor array. Value interpolate(const Score& v, Phase ph, ScaleFactor sf) {